Thin Films and Multilayers for Shielding Applications.*

Tailoring of electromagnetic properties of synthetic magnetic structures is advantageous for high frequency applications, such as shielding materials in magnetic recording, where characterisation in the gigahertz frequency range is necessary to determine parameters for simulations and aid component design. We present a systematic study of the effect of process conditions and stoichiometry on the ferromagnetic resonance (FMR) and spin wave properties [1][2] of Ni_xFe_100-x alloy thin films fabricated by magnetron sputtering. The FMR response and high frequency parameters such as Gilbert damping are particularly affected across the fcc/bcc phase transition, improving with increasing Fe content. Effects of modulating stoichiometry were also studied using bilayer superlattice structures with constant total thickness of the form n[Ni_xFe_100-x], where n is the number of bilayers and determines the period of modulation. Compared to single layers of the same net composition, the superlattices were seen to enhance the magnetic properties. [1] Y. Ding. J. Appl. Phys. 96. (2004) [2] Y. V. Khivintsev. J. Appl. Phys. 108 (2010)